Synthesis of 2'-deoxy-1-deazawyosine: A stabile 2'-deoxyisostere of a rare trna constituent

2'-Deoxy-1-deazawyosine (3a), an isostere of the rare tRNA constituent wyosine (la) and its α-anomer have been synthesized via glycosylation of the nucleobase 5a with the halogenose 6. In contrast to the labile parent 1a, the isostere is highly stabile against hydrolysis even as 2'-deoxynuclcoside. The stability of 3a is due to the low susceptibility of the pyrrol ring to protonation. The rapid hydrolysis of wyosine (la) compared to guanosine is explained by a favoured solvatization of the molecule being freezed in the anti-conformation.